Gas-operated well apparatus with expansion retarding device



July 7, 1953 Flled Sept 20, 1948 Patented July 7, 1953 GAS-OPERATED WELLAPPARATUS WITH EXPANSION RETARDING DEVICE ReubenC. Baker, Goalinga,Caliii,v assignor. to Baker Oil Tools, Inc., Vernon, Calif., acorporation of California Application September 20, 1948, Serial No.50,194

Claims.-

The present invention relatestowell ,devices,. and more particularly tosub-surface, devices. or.-

apparatus employed in gas' and similar wells;

Certain types of sub-surface well apparatus are operated by gaspressure. Compressed air;

bore holes, such. as, oil,

hydrogen, acetylene, products of combustion and the like may constitutethe motivating gaseous force. The compressedgas may not only operate thewell apparatus, but may also eifeot release of the apparatus, or'part ofit, from the well bore, to enable its withdrawal to the top of the well.

Heretofore; release of'all, or a portion, of the apparatus has permittedthe gas, which might be under comparatively high pressure, to expandsuddenly, imposing severe shock loads on the equipment, and, :attimes,inflicting damage on some of its parts; I

Accordingly, an object of the present invention isto provide improvedgas operated sub-surface well apparatus, which is capable-ofretard ingexpansion of the motivating gaseous me-- diu-m without preventing properoperation of the-apparatus.

Another object of the invention is to provide gas 'operatedsub-surfacewell apparatus, which is capable of' retarding expansion of themotivating gaseous-medium without-preventing full expansion of themedium within the limitations of the equipment;

Still another object of the'invention is vent sudden expansion of thegas which oper ates subsurface-apparatus; upon release of" a:.= largeportion ofthe load on theapparatus, with out preventing the gas fromexpanding fully" within the limitations of theequipment.

A further object ofthe invention is' -to-provide gas operated-wellapparatus capable-of'per forming its functions without substantialinterference from the hydrostatic head" of fluid in thewell bore, butwhich still utilizes such hy drostatic head in preventingsuddenexpansion. of the gas in the apparatus after'the load: on

the apparatus-has beenreleased or reduced sud-. denly.

This invention possesses many other advalh tages, and has other objectswhich'may'be made" more clearly apparent from: a. considerationoi.v aform in which it may be embodied. This:

form is shown in the-drawingsaccompanying and forming part of thepresent specification.

It will now bedescribed in detail, ,forythe purposeof I illustratingthev general; principles: of: the invention'; but it". is" tobe.understood. that suchtopredetailed descriptionis not to be-taken in alim--,

iting sense,- since the scope of the inventionis best defined by theappended claims;

Referring to the drawings:

Figures la and 1b together'constitute a longitudinal section through awell apparatus p0- sitioned in a Well casing, with the partsoccupyingtheir-initial position for lowering theap---. paratusthrough the casing,Fig. 1b forming. a"

lower continuation of Fig, In;

Figs. 2a and Zb-are views'similar to Figs. 1a-

In the form of the invention disclosed in they drawings, it is desiredto run a well packer A- to a desired location in a well casing Bdisposed.

within 'a bore hole. The packer is then anchored in packed-off conditionagainst thewell casing through use of a setting tool C connect ed to it.This settingtool is attached to the lower end of a running-in string,such as-a wire,

line D extending to the top of the well bore.

The well packer A may assume any desired form. The one. disclosed in thedrawings includes a tubular main body [0 whose central passage ll maybe-closedby a plug 12. A guide l3v is secured to. the lower end of thebody, to prevent. hanging up, of, the tool in the casing bore orcoupling spaces duringv its lowering'in. the,

- well casing B.

The well, packer can be anchoredagainst the downward movement in thewell casing by a plurality of lower segmental slips l4 engaging theguide I3. and the lowerxabutment or flange 15 on the body. The, inner.surfaces l6 of these slips are tapered in a downward and inwarddirection for slidable engagement with a corresponding, or externallytapered, surface "@011 a frusto-conic-al expander I8-slidable on thebody.

This expander is connected to thelower end of f apacking sleeve l9.,,ofrubber or similarmate: rial, disposed around the body Ill, the upper endof this packing. sleeve being connected toan upper expander 20 having anupwardly and in-.

wardly inclined externally tapering surface 2] engageable withcorresponding tapered surfaces 22 on a plurality of upper segmentalslips 23.

ing them to their associated upper and lower expanders 2B, [8.

The shear screws 26 attaching the upper slips 23 to the upper expander20 have acombined shearing strength which is substantially less than theshear value of the screws 24 holding the upper expander to the body l0.These latter screws have a lesser shear value than the screws 25, 2'!securing the lower expander E8 to the body, and the lower slips 14 tothe lower expander. These relative shear values are selected to secured8.-

tachment, at first, of the upper slips 23 from the upper expander 20,and the movement of the upper slips downwardly along the upper expanderand radially outward into anchoring engagement:

with the casing wall. A subsequent upward strain or pull on the packerbody [D then shears the screws 24 holding the upper expander 29 to thebody ID, and moves the lower expander l8 and slips l4 with the bodytoward the upper expander 28 and slips 23, in order to efiectcompression of the packing l9 between the expanders and its outwardexpansion into firm sealing engagement with the wall of the casing.

Thereafter, an increase in the upward pull or force on the packer bodyIt) substantiall simultaneously shears the screws 25, 21 holding thelower expander I8 to the body, and the lower slips M to the lowerexpander, to cause the lower flange I5 and, guide 13 on the body toshift the lower slips [4 upwardly along the lower expander and radiallyoutward into anchoring engagement with the wall of the casing B. A splitretractor ring 28 may be disposed in the expander for engagement withone of several buttress thread ratchet teeth 29 formed on the exteriorof the body IE], to lock the latter against downward movement (see Fig,2b)

In the form of invention disclosed in the drawings, setting of the wellpacker A is dependent upon the development of a gas pressure within a'setting tool C initially secured to the well packer, This gas pressureis developed within a cylinder 30, consisting of a general cylindricalsleeve 3|, an upper head 32 threaded into the sleeve, and also a lowerhead 33 threadedinto the sleeve. Leakage from the, oylinder'through thethreaded connections may be prevented by suitable side seals 34, inperipheral grooves end of a piston rod 43 is threadedly connected to thepiston, the rod extending downwardly through the lower cylinder head 33to a point therebelow, where an anvil or cross-piece 44 is mountedwithin a transverse slot 45 in the'rod. Leakage between the rod 43 andlower cylinder head 33 is prevented by suitable rod packing in the formof one or more round rubber, or rubberlike, seals 46, engaging theperiphery of the rod, and disposed within suitable ring'grooves 41 in 4the head 33. The packing rings 46 prevent leakage of liquids from thewell casing into the cylinder 30 below the piston 45, insuring that airunder atmospheric pressure is present below the piston when theapparatus is assembled and lowered in the well casing. v v v It isdesired to transfer the downward movement or force of the piston 40 andthe piston rod 43 to the upper slips 23 of the packer, and the relativeupward movement of the cylinder 30 to the packer body l0,in order toobtain the desired anchoring of the packer in the well casing. To

accomplish this purpose, a tubular actuating mandrel 48 is threadedlconnected to the lower end of the lower cylinder head 33. The lower end5E! of the mandrel is secured to a sleeve 49, threaded into the upperend of the body 10, through the agency of a frangible connecting pin 5 lAs specifically disclosed, the lower end of the mandrel is of reduceddiameter and is piloted within the sleeve 49,the pin extendingtransversely through the sleeve 49 and piloted mandrel portion50.

The piston rod 43 is movable downwardly within the bore 52 of theactuating mandrel 48, the cross-piece 44 projecting in oppositedirections from the rod through diametrically opposed, j

longitudinally extending slots 53 formedthrough the mandrel wall. Thecross-piece also extends 1 into opposed slots 58, formed throughasetting ring or sleeve 56 slidably mounted on the actuating mandrel 48,to form a connection between the piston rod 33 and the setting ring 56.1A setting sleeve or skirt 5'! is adjustably threaded on' the settingring, its lower end 59 engaging-the tops of the upper slips, 23. v w

A fluid or gaseous force is developed within the cylinder 30 above thepiston 40. This force moves the piston and piston rod 43 downwardly,and'the cylinder 30in a relative upward direction. The downwardmovementof the rod 43 is transmitted to the setting sleeve or skirt51 throughthe anvil 44 and setting sleeve 55; whereas, the upward movement of thecylinder 30 is,

transmitted to the packer body 10 through the actuating mandrel 48,frangible pin 51,. and the sleeve 49. Accordingly, it is apparent thatthe development of sufiicient pressure in the cylin-.:

der 30 will eventually shear the screws 26 holding the upper slips 23 tothe expander 20, and move the slips outwardly against the casing B.Thereafter, the cylinder 30 will move upwardly, to pull the body ID inthe same direction, for the purpose of "expanding the-packing sleeve l9against the casing B, and then the lower slips I4 against the above.

In order to obtain the desired operational sequence, a combustible fuel69 may be contained within the upper end of the cylinder 30. Thecombustion charge, such as a railway flare of cylindrical or stick form,is placed in the head end 32 of the cylinder within a combustion chamber10 formed therein. This combustion charge is ignited by a blankcartridge H contained within a gun barrel 12 inserted within the upperend of the cylinder head 32. Leakage between the barrel and head isprevented by a suitable side seal 13 on the barrel engaging the wall ofthe The barrel [2 is threaded into a firing head, which, in turn, isthreadedly secured to the upper end of'the cylinder head 32. The wireline running-in string D is suitably secured to the firing head'74, in aknown manner, and has, the lower,

cas ng, in the manner described end of its electrically conductive wireor core connected electrically to a heating filament 13 contained withinthe cartridge H.

The apparatus is lowered in the well bore with the parts disposed in theposition shown in Figs. 1a and lb. When the point in the casing isreached at which the well-packer A is to be set, the circuit through thecartridge filament I6 is completed, which fires the cartridge H. Theflame issuing therefrom ignites the upper end of the combustible charge69, initiating its combustion. The charge burns and develops a gaseouspressure within the cylinder 30. As the pressure increases, the piston40 is urgeddown-v wardly and the cylinder 3:] relatively upwardly. Theforce of the piston 40 is transmitted through the rod 43, cross-piece 44and setting ring 56 to the sleeve 51, which bears against the upperslips 23. When sufficient pressure has been developed within thecylinder to overcome the shear strength of the screws 26, and also thehydrostatic head of fluid acting upwardly on the piston rod 43, theslips 23 are released from the expander and are pushed downward- 1yalong the latter into outward engagement with the casing B. v

As the combustible charge continues to burn. the gas pressure withincylinder increases to a further extent. Since the upper slips 23 arewedged against the casing B, the piston can,- not move downwardly to anyfurther appreciable extent. Instead, the cylinder 35, actuating mandrel48, sleeve 49, and packer body II] are urged in an upward direction.When the pressure and force within the cylinder has increasedsuificiently to overcome the shear strength of the screws 24 holding theupper expander 2!! to the body, such screws are disrupted and the packerbody In is moved upwardly within the upper expander 20 to compress thepacker sleeve l9 between the upper and lower expanders 23, I8, forcingit into firm sealing engagement with the casing wall.

If the cylinder gas pressure increases further, as a result of thecontinued combustion of the charge 69, the screws 25, 21, attaching thelower expander Hi to the body In and the lower slips-l4 to the lowerexpander, are disrupted, allowing the cylinder 30 to move upwardly andcarry the body I!) and lower slips l4 in an upward direction, to shiftthe latter radially outward into engagement with the casing B. Thepressure in the cylinder continuest increase as combustion of the charge69 proceeds, and all of the packer elements are engaged more firmly withthe casing B. When the pressure A, the piston has not been moveddownwardly. to its fullest extent within the cylinder 39.

Shearing of the pin 5| releases the load on the cylinder 30 and piston40, and ordinarily allows the gas in the cylinder to partake of a suddenexpansion, which shifts the piston '40 relatively downwardly to theextent limited by its engagement with the lower cylinder head 33.

When it is realized that comparatively high pressures, of the order of5000 p. s. i. and higher, may be developed in the cylinder 3|), in orderto disrupt the connector pin 5|, it is evident that a tremendous blowwould be struck by the piston 40 upon the cylinder head 33. The reactionof this blow and the sudden movement of the cylinder 3|] and piston 40introduce a recoil or shock load on all of the equipment in the wellbore, which sometimes results in damage to some of the parts.

The present invention overcomes the above noted disadvantages. A liquid80, preferably of a non-combustible variety, such as water, is placed inthe cylinder 30 below the piston 40. The liquid level 8| terminates asubstantial distance belowv the lower end of the piston, in order topermit 5 relative downward movement of the piston in the cylinder inefiecting full setting of the well packer A against the casing B andshearing of the frangible connector pin 5|, which releases the settingtool C from the bridge plug. The liquid level 8| is so chosen that thelower end of the piston is closely adjacent the liquid in the cylinderwhen the frangible pin 5| is sheared. Following such shearing, thepiston 4|) may move relatively downward to a further extent, until itengages theupper end of the liquid column 80 in the cylinder. Before thepiston can move downwardly in the cylinder to any further extent; itmust displace or force this liquid from the cyline der 30; otherwise,the piston must remain on top of the incompressible liquid 80.

It is apparent that the liquid 80 prevents further relative downwardmovement of the piston 45 within the cylinder 35, and does not permitthe piston to move downwardly to the full extent determined by itsengagement with the lower cylinder head 33. As a result, the gaseousmedium in the cylinder cannot expand to any appreciable extent after theconnector pin 5| has been sheared, and is incapable of imparting asubstantial velocity to the parts of the setting tool C, which imposethe shock loads on the apparatus referred-to above. Thus, the liquidlevel can be used to regulate the length of the downward move-. ment ofthe piston in the cylinder.

Although the liquid medium 80 can be used for the latter purpose and toprevent sudden and full expansion of the gaseous medium, it is preferredto displace such liquid medium in a comparatively slow manner from, thecylinder 30 after, it has been engaged by the piston 40.

As indicated above, air at substantially atmospheric pressure isinitially contained in the cyl-- inder 35 between the piston 40 and theliquid medium Bil. The gas underpressure in the cyl inder above thepiston will, of course, compress this air during downward movement ofthe piston 40 in the cylinder, and it must also overcome the hydrostatichead of fluid in the well casing acting upwardly across thecross-sectional area of the piston rod 43. The area of this rod,however, is substantially less than the cross-sectional area of thepiston 45; so-that only a slightly additional load is imposed by thehydrostatic head upon the apparatus, which must be overcome by thecom--v bastion gas under pressure. The hydrostatic head of fluid isprevented from entering the cylinder 30 below the piston why the variouspacking rings 46 around the piston rod 43 and by othersuitable sealrings 35.

' Despite the fact that the hydrostatic head does not substantiallyinterfere with the operation of the apparatus, it is still desired totake advan-. tage of this hydrostatic head in cushioning the equipmentafter theconnector pin 5| has been disrupted. It is also desired toutilize the liquid 80 in the cylinder 30 below the piston 40 as acushioning medium, by allowing it to escape, comparatively slowly, fromthe cylinder 30 upon its engagement by the piston 40.

For the purpose of accomplishing the above noted purposes, a port ororifice 82 is provided in the cylinder sleeve 3| adjacent the lowercylinder head 33. This port or orifice is of relatively smallcross-section and is initially closed by a plug 83, made of steel orother suitable material. The plug is of the type that can be forcedoutwardly by the liquid 8!! in the cylinder upon its being subjected tosufficient pressure, but it cannot be forced inwardly by the hydrostatichead of fluid in thewell casing. As specifically disclosed, the plug 83has an inner cylindrical portion 84 received within a companioncylindrical bore portion of the orifice 82, there being a suitable sealring 85 in the cylinder sleeve 3! engaging the cylindrical plug portion84 to prevent leakage therealong in both directions. The plug isprevented from being shifted inwardly by the hydrostatic head of fluidby tapering its outer head 86 and causing this tapered portion to engagea companion seat 81 in the cylinder sleeve.

It is apparent that the hydrostatic head of fluid is prevented fromentering the cylinder 30 below the'piston 40 by the plug or closuremember 83. However, after the well packer A has been set in the wellcasing B and the connector pin sheared, the piston 45 moves a slightdistance downwardly into engagement with the liquid 80 in the cylinder,the pressure of the gas in the cylinder above the piston beingtransmitted to the cushioning liquid 80, and from this liquid to theplug 83. When sumcient force has been exerted to overcome thehydrostatic head of fluid in the well casing, the plug 83 is blown outof the orifice 82, which then allows the cushioning liquid 80 to escapefrom the cylinder 30. Such escape is not instantaneous because of therestricted area of the orifice 82, the piston 40 lowering in acomparatively gradual manner under the impetus of the gaseous medium,and eventually coming to rest against the lower cylinder head 33, orimmediately thereabove.

Thus, the cushioning liquid 80, by being exhausted in a gradual mannerthrough the orifice 82, retards expansion of the gaseous medium byslowing down the rate at which the piston 40 can approach the lowercylinder head 33. Accordingly, the gaseous medium does not expandsuddenly after disruption of. the connector pin 5|, which prevents shockloads from being imposed on the equipment. Not only does the liquidmedium 80 function as a cushioning agent in preventing sudden expansionof the gaseous medium upon release of the load on the setting tool C,but the removal of the plug 83 from the orifice 82 subjects the entirecross-sectional area of the piston 40 to thehydrostatic head of fluid inthe well casing, thereby introducing further retarding forces to fullmovement of the piston 40 to its lowermost position in the cylinder 30.

It is, accordingly, apparent that apparatus has been provided forpreventing damage to the equipment; which cushions the shock incident tosudden release of the load on the apparatus; and which prevents suddenexpansion of the generating gases by limiting the extent to which suchgases can move the parts of the apparatus, following release of the loadon the apparatus; or by retarding the rate at which such gases can movethe apparatus parts, following release of the load to which it has beensubjected.

The inventor claims:

1. In well apparatus: a well device adapted to be operated in a wellbore; fluid actuated prime moving means operatively connected to saidwell device and adapted to be lowered in the well bore with said deviceto operate'the same therewithin, comprising a cylinder and piston meansslidable in said cylinder; means sealing a crosssectional area of saidcylinder to provide a completely enclosed space in said cylinder on thelow pressure side of said piston means and to prevent the well fluidexternally of said cylinder from entering said enclosed space duringlowering of the apparatus in the well bore; means providing a motivatingforce in said cylinder on the 'high. pressure side of said piston meansto slide said piston means relatively in said cylinder; and a fluidmedium in said enclosed space on the low pressure side of said pistonmeans engageable by said piston means for arresting relative movement ofsaid piston means in said cylinder, said fluid medium comprising aliquid.

2. In well apparatus: a well device adapted to be operated in a wellbore; fluid actuated prime moving means operatively connected to saidwell device and adapted to be lowered in the well bore with said deviceto operate the same therewithin, comprising a cylinder and piston meansslidable in said cylinder; means sealing a cross-sectional area of saidcylinder to provide a completely enclosed space in said cylinder on thelow pI'BS-. sure side of said piston means and to prevent the well fluidexternally of said cylinder from entering said enclosed space duringlowering of the apparatus in the well bore; means providing a motivatingforce in said cylinder on the high pressure side of said piston means toslide said piston means relatively in said cylinder; and a fluid mediumin said enclosed space on the low pressure side of said piston meansengageable by said piston means for arresting relative movement of saidpiston means in said cylinder, said fluid medium comprising a liquid,there being a space initially between said liquid and piston means toallow initial movement of said piston means In said cylinder free frominterference from said liquid.

3. In well apparatus: a well device adapted to be operated in a wellbore; fluid actuated prime moving means operatively connected to saidwell device and adapted to be lowered in the well bore with said deviceto operate the same therew thin, comprising a cylinder and imperforate pston means slidable in said cylinder; means closing said cylinder toprovide a closed space therewithin on the low" pressure side of saidpiston means and to prevent well fluid externally of said cylinder fromentering said closed space during lowering of the apparatus in the wellbore said cylinder having an orifice on the low pressure side of saidpiston means; means providing a motivating force in said cylinder on thehigh pressure side of said piston means to slide said piston meansrelatively in said cylinder; closure means closing said orifice againstentr of well fluid into said cylinder from the exterior of saidcylinder; a fluid medium in said closed space on the low pressure sideof said piston means engageable by said piston means for opening saidclosure means and arresting relative movement of said piston means insaid cylinder, said fluid medium comprising a, liquid, there being aspace initially between said liquid and piston means to 9 allow initialmovement of said piston means in said cylinder free from interferencefrom said liquid.

4. In well apparatus: a well device adapted to be operated in a wellbore; fluid actuated prime moving means operatively connected tosaidwell device and adapted to be lowered in the well bore with said deviceto operate the same therewithin, comprising a cylinder and imperforatepiston means slidable in said cylinder; means closing saidcylindertoprovide a closed space therewithin on the low pressure side ofsaid piston means and to prevent well fluid externally of said cylinderfrom entering said closed space during lowering of the apparatus in thewell bore means providing a motivating force in said cylinder above saidpiston means to slide said piston means relatively downward in saidcylinder; and

a fluid medium in said closed space below said piston means engageableby said piston means for arresting relative downward movement of saidpiston means in said cylinder, said fluid medium comprising a liquid.

5. In well apparatus: a well device adapted to be operated in a wellbore; fluid actuated prime moving means operatively connected to saidwell device and adapted to be lowered in the well bore with said deviceto operate the same therewithin, comprising a cylinder and piston meansslidable in said cylinder; means closing said cylinder to provide aclosed space therewithin on the low pressure side of said piston meansand to prevent fluid from entering said closed space; said cylinderhaving an orifice in its lower end; an outwardly removable pluginitially closing said orifice; means providing a motivating force insaid cylinder abov said piston means to slide said piston meansrelatively downward in said cylinder; and a fluid medium in said closedspace below said piston means engageable by said piston means fordisplacement through said orifice to arrest relative downward movementof said piston means in said cylinder, said fluid medium comprising a,liquid.

6. In well apparatus: a well deviceadapted to be operated in a wellbore; fluid actuated prime moving means for operating said well deviceand adapted to be lowered in the well bore with said device to operatethe same therewithin, comprising a cylinder and piston means slidable insaid cylinder; means sealing a cross-sectional area of said cylinder toprovide a completely enclosed space in said cylinder on the low pressureside of said piston means and to prevent the well fluid externally ofsaid cylinder from entering said enclosed space during lowering of theapparatus in the well bore; means releasably securing said fluidactuated means to said well device; means providing a motivatingforce'in said cylinder on the high pressure side of said piston means toslide said piston means relatively in said cylinder; and a fluid mediumin said enclosed space on the low pressure side of said piston meansengageable by said piston means for arresting relative movement of saidpiston means in said cylinder upon release of said securing means, saidfluid medium comprising a liquid.

'7. In well apparatus: a well device having normally retracted meansengageable with a well casing; fluid actuated prime moving means forexpanding said normally retracted means against the casing, comprising acylinder and a piston slidable in said cylinder, means closing saidcylinder to provide a closed space therewit-hin on the low pressure sideof said piston and to prevent well fluid externally of said cylinderfrom entering said closed space during lowering of the apparatus in thewell casing; said cylinder having an orifice therein on the low pressureside of said piston and closure means normally closing said orificeagainst entry of fluid into said cylinder from; the exterior thereof;means releasably securing said fluid actuated means to said well device;and a fluid medium in said closed space engageable with said piston forretarding relative movement of said piston in said cylinder, said fluidmedium, comprising a liquid subject to pres-.- sure by said piston toeffect opening of said closure means and to be expelled from saidcylinder through said orifice, there being a space initially betweensaid liquid and piston to allow initial movement of said piston in saidcylinder free from interference from said liquid until after release ofsaid securing means.

8. In well apparatus: a well device having normally retracted meansengageable with a well casing; fluid actuated prime moving means forexpanding said normally retracted means against the casing, comprising acylinder and a piston slidable in said cylinder, said cylinder andpiston providing a closed fluid tight space on the low pressure side ofsaid piston into which Well fluid externally of the cylinder cannotenter during lowering of the apparatus in the well casing, said cylinderhaving an orifice therein on the low pressure side of said piston andclosure means normally closing said orifice against entry of well fluidexternally of said cylinder into said closed space; means releasa-blysecuring said fluid actuated means to said well device;-and a fluidmedium in said closed space engageable with said piston for retardingrelative movement of said piston in said cylinder, said fluid mediumcomprising a liquid subject to pressure by said piston to effect openingof said closure means and to be expelled by said piston from saidcylinder through said orifice.

9. In well apparatus; a well device having a body and normally retractedmeans for engagement with a well casing; fluid actuated means forsetting said device in said well casing comprising a piston means forexerting a downward force on said normally retracted means and acylinder for exerting an upward force on said body; said cylinder andpiston means providing a closed fluid tight space on the low pressureside of said piston means; frangible means for transmitting said upwardforce between said cylinder and body; said cylinder having an orifice atits lower end; closure means for preventing entry of fluid through saidorifice into said cylinder; and a fluid medium in said closed spacebelow said piston means for shifting said closure means to open positionupon being subjected to pressure by said piston means, said fluid mediumcomprising a liquid spaced initially from said piston means andengageable by said piston means after disruption of said frangible meansto be expelled by said piston means from said cylinder through saidorifice.

10. In well apparatus: a well device having a body and normallyretracted means for engagement with a well casing; fluid actuated meansfor setting said device in said well casing comprising a piston meansfor exerting a downward force on said normally retracted means and acylinder for exerting an upward force on said body; said cylinder andpiston means providing a closed fluid tight space on the low pressureside of said piston means; frangible means for transmitting said upwardforce between said cylinder 'fiuid through said orifice into saidcylinder; and

a fluid medium in said closed space, said medium being spaced initiallya substantial distance below said piston means and adapted to besubjected to the pressure of said piston means, upon disruption of saidfrangible means, to shift said closure means to orifice opening positionand retard relative movement of said piston means in said cylinder, saidfluid medium comprising a liquid ejectable by said piston means throughsaid orifice and from said cylinder.

, REUBEN C. BAKER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date Scott July 15, 1913 Flynn Apr. 21, 1936 Wells et a1 Apr. 6,1937 Coshow Dec. 28, 1937 Baker Nov. 7, 1939 Broyles Feb. 13, 1940Futral July 6, 1943 Baker Apr. 3, 1945

